The Baroque guitar is a guitar from the baroque era (c. 1600–1750), an ancestor of the modern classical guitar. The term is also used for modern instruments made in the same style.

The instrument was smaller than a modern guitar, of lighter construction, and had gut strings. The frets were also usually made of gut, and tied around the neck. A typical instrument had five courses, each consisting of two separate strings although the first (highest sounding) course was often a single string, giving it a total of nine or ten strings.

The conversion of all courses to single strings and the addition of a bass E-string occurred during the era of the early romantic guitar.

Three different ways of tuning the guitar are well documented in seventeenth century sources as set out in the following table. This includes the names of composers who are associated with each method. Very few sources clearly indicate that one method of stringing rather than another should be used and it may have been up to the player to decide what was appropriate.